Most Orchids are hemi-parasitic on underground fungi, obtaining some of their nutrients from the fungus whilst not benefiting the fungus in any known way (if both benefited, it would be 'mutualistic' [formerly known as 'symbiotic']). The fungal microrrhizal hyphae filaments penetrate parts of the orchid and supply it with energy, but certain parts of the orchids, such as the tubers and other storage organs, possess phytoalexins which are toxic to the fungi and thus penetration there is highly discouraged. The hyphae, which penetrate some cells of the orchid, form loops and coils within them called 'pelotons'. At intervals the orchid digests the pelotons absorbing the nutrients: water, carbohydrates, mineral salts and other organic materials. The main fungal associates with orchids are the Basidomycetes and Rhizoctonia groups of fungi (some other members of the latter group are soil saprotrophs or pathogens). Thus orchids cannot be made to grow just anywhere, most require a fungal donator to be present in the soil. Many orchid seeds may lie dormant in the soil for up to 10 years before the correct fungus comes along.

Some species of orchid are highly specific, able to use just one particular fungus (orchids belonging to the Spirantes, Goodyera and Liparis genera), but most are not really that bothered and can utilise many species of fungi, sometimes many more than one at once. Those orchids that are dependent upon just one fungus are usually rare, because they simply will not grow without it that one fungus, Burnt-tip Orchid being a good example.

Most orchids can also photosynthesize once above ground; most have green leaves containing chlorophyll, but still continue to supplement their needs with the aid of fungal hyphae. But there are a few orchids which are totally dependent upon the fungus even when the aerial parts are extant, such as Coralroot Orchid, Ghost Orchid, Bird's-nest Orchid and Yellow Bird's-nest Orchid, since they lack chlorophyll altogether. The latter orchids are thus fully saprophytic.

Another cross-genus hybrid is that between Green-winged Orchid (Anacamptis morio) and Early-purple Orchid (Orchis mascula) which is from a differing genera (although both are in the same family). The resulting cross is called X Anacamptorchis morioides. It too is shown in a green square on the forbidden diagonal.
There are thus no species belonging to the Anacaptis Genus which do not (at the moment) hybridize (with something).

The Gymnadenia genus exhibits no same-genus hybrids, but has three inter-genus hybrids.
The first is between Chalk Fragrant-orchid (Gymnadenia conopsia) and Small-white Orchid (Pseudorchis albida), the hybrid has no other name other than Pseudoorchis albida x Gymnadenia borealis.

Two others occupy the same green square, for both are hybrids with Heath Fragrant-Orchid (Gymnadenia conopsea):
The first of these being with Pyramidal Orchid (Anacamptis pyramidalis) yielding the hybrid X Gymnanacamptis anacampti
The second being with Early Marsh-orchid (Dactylorhiza incarnata), the result having no other name than Dactylorhiza incarnata x Gymnadenia conopsea.

Orchis anthropophera was formerly in another genus, Aceras and was then called Aceras anthropopherus (note the subtle change in the name ending too), but has since been moved into the Orchis Genus, where it's hybrid with Monkey Orchid (Orchis simia) no longer makes it an inter-genera hybrid.

There is, however, another Orchis species that does indeed cross hybridize with another Genus, that of Orchis mascula (Early-Purple Orchid) which crosses with Anacamptis morio (Green-winged Orchid) to produce the cross-genus hybrid X Anacamptorchis moroides. This hybrid is shown in a green square, occupying a position on the forbidden diagonal of the chart which is just a convenient place to put it.

The Helleborines are in two genera, the Cephalanthera, and the Epipactis, the main difference between the two being that Cephalanthera species have flowers that do not fully open so the un-spurred lip is often hidden whereas the un-spurred lips of Epipactis species are easily visible.

The Helleborines are in two genera, this the Cephalanthera, and the Epipactis, the main difference between the two being that Cephalanthera species have flowers that do not fully open so the un-spurred lip is often hidden.